1. Field of the Invention
The present invention pertains to a detection system and method, and more particularly to a flexible platform for scanning and sensing and related method for identification of a target within a detection field.
2. Description of the Related Art
Photoelectric scanners and sensors are widely used in industrial applications for detection, measurement, identification and differentiation of objects. Sensors might for example incorporate a photoelectric transmitter and receiver that detects the presence or absence of varying amounts of light transmitted from the transmitter and received by the receiver as an indication of the presence or absence, type, or position of an object. Scanners might for example incorporate multiple transmitter and receiver channels, which are scanned one after another to determine the presence or absence of varying amounts of light transmitted from an individual transmitter and received by a corresponding receiver.
Industrial scanners are most commonly made in the form of two bars, with one bar containing receivers and another bar containing transmitters. In a typical application the bars are positioned in such a manner as to form a light curtain, consisting of a multitude of light beams between individual emitters and receivers. When an object to be detected blocks all or a portion of the light curtain, the scanner indicates the presence of such an object by asserting its output. Another common implementation of the scanner is in the form of a single bar where both the receiver and transmitter are integrated adjacent to each other within the same housing. In this case, the light curtain is formed with a retro-reflective tape mounted opposite of the scanner. Another common implementation of an industrial scanner is in the form of a fork or rectangle, with transmitters and receivers mounted opposite of each other to form a light curtain. One of the limitations of present scanner architectures is that the distance between the transducer elements within each bar is fixed, and consequently so is the dimension of the detection profile. To meet the demands of high resolution (close beams) and height of coverage (long scanners), a multitude of models must be manufactured. Furthermore, the user is not able to customize beam location and is therefor unable to achieve a desired mix of resolutions and detection profiles. These restrictions dramatically increase cost and drastically reduce overall penetration of the scanner technology into industrial sensing applications.
In many applications, scanners are required to perform an operation or suspend execution of an operation in response to external input. An example of such an operation is a measuring scanner, whose measurement timing is determined by the stand-alone sensor used as an event trigger. Practical implementation of this relatively simple application requires the use of a stand-alone scanner, a stand-alone controller, such as a Programmable Logic Controller, and a stand-alone sensor. The complexity and cost, as well as multiple potential failure points of such an installation, limits the use of such present scanners to areas where no alternatives are practical. Mechanical installation requirements of present scanners, which tend to be large and bulky, are incompatible with relatively small areas allocated to sensing equipment and therefor further limit penetration of the scanners into applications traditionally dominated by sensors. The performance of present scanners is highly limited by the sequential nature of their architecture, where each individual element is activated one after another until a complete scan is performed. Such architecture neither allows for any part of the scanner to function at a response time that is different from the remainder of the scanner nor does it allow for flexible assignment of scanning sequences. Although flexible scanning capability is highly desirable in more traditional scanning applications, especially as it relates to the combination of scanning and sensing, it is essential for sensing equipment that incorporates multiple mechanisms of sensing, such as photosensors, IR, RF ultrasound etc, where the difference in response times of the transducers is substantial.